According to international animal health authorities, disease surveillance in livestock and poultry has as its main purpose the early detection of diseases and disease outbreaks. It also plays an important role during outbreaks, such as monitoring how fast a disease is spreading through animal populations and in what direction. Disease surveillance is also critical in determining how effective efforts have been in controlling and eradicating disease from a particular area or animal population and in recognizing when that disease no longer poses an immediate threat to animal or human health.